Fukushima nuclear crisis - blogger briefing

You may be looking for useful information about the ongoing nuclear emergency at Japan’s Fukushima 1 nuclear power plant. Here are some answers to common questions about the situation - along with useful links. Please feel free to share this information online or in conversations.
Click on the question to reveal the answer below  
  • I heard there was never any reason to worry. Why are news agencies, environmental groups and governments making such a big deal out of this?

    There have been explosions at several nuclear reactors, repeated failure of emergency cooling systems, power failures and radioactive materials released into the atmosphere. Hundreds of thousands of people have been evacuated, thousands more asked to stay indoors, close their windows and turn off ventilation. Iodine tablets have been issued to the local population. It is irresponsible and utterly false to describe this as anything except a serious nuclear crisis. At the time of writing, the situation is still not under control. The hours and days ahead will be critical.

  • What is the worst case scenario? How bad can it be? And how close are we (or did we) come to this?

    While it is difficult in this situation to rule out further earthquakes and other factors, at the moment the worst case could arguably be ongoing dramatic overheating in reactor number two where the containment vessel is already breached. This could lead to more radioactive material being released into the environment from the nuclear fuel elements. The spent nuclear fuel pools at all four reactors are exposed to the air and in unit four there are reports that the cooling water is boiling. This Scientific American article has more details.

  • How does this situation compare to Three Mile Island or Chernobyl?

    This incident is already worse than Three Mile Island. Both the Japanese and French nuclear authorities are saying that the radioactive contamination is significant. The French nuclear authority (ASN) is suggesting this accident is level 5 or 6 on the International Nuclear and Radiological Event Scale  (INES)  instead of level 4 as previously announced. A level 4 incident is described as an ‘accident with local consequences’. Level 5 is an ‘accident with wider consequences’. Level 6 is a ‘serious accident’. The accident at Chernobyl was a Level 7, a ‘major accident’.

    For example :

    - The Kyshtym disaster at Russia’s Mayak nuclear fuel processing plant in 1957 (INES Level 6) whose effects are still being felt to this day.

    - Three Mile Island in 1979 (INES Level 5)

    - The Tokaimura nuclear accident in 1999 (INES Level 4) where two workers died after being exposed to a nuclear criticality.

    - The Bohunice nuclear accident in 1977 (INES Level 4) whose true consequences were covered up by the Soviet authorities.

    - The near-meltdown of one of the reactors at Sweden’s Forsmark nuclear power plant in 2006 was rated at Level 2.

    The emergency at Fukushima is at the higher end of the scale in terms of consequences.

    The International Atomic Energy Authority explains how the INES scale works here.

  • Is this already a disaster? What harmful effects have already happened? What are the possible long term impacts on soil, animals, agriculture etc.?

    It is a disaster but the full extent is unknown. The question is not whether this qualifies as a disaster, it's a question of how big, how many people are effected and how long it will take to get under control. Only then can we start talking about remediation.

    Already the authorities have reported radioactive contamination outside the reactors site, at the moment most attention is being focused on two radioactive elements: Iodine-129 and Caesium-137 contamination in particular.

    Here is Time magazine on on iodine contamination:

    When thyroid cells absorb too much radioactive iodine — either through the air or through contaminated food — it can increase the risk for thyroid cancer, says the American Thyroid Association. Babies and young children are at highest risk as their thyroid glands are most radiation-sensitive. People over 40 are at less risk.

    Here is the US Environmental Protection Agency on Caesium-137 contamination:

    People may ingest caesium-137 with food and water, or may inhale it as dust. If caesium-137 enters the body, it is distributed fairly uniformly throughout the body's soft tissues, resulting in exposure of those tissues. Slightly higher concentrations of the metal are found in muscle, while slightly lower concentrations are found in bone and fat. Compared to some other radionuclides, caesium-137 remains in the body for a relatively short time. It is eliminated through the urine. Exposure to cesium-137 may also be external (that is, exposure to its gamma radiation from outside the body).

    Like all radionuclides, exposure to radiation from cesium-137 results in increased risk of cancer.

    This is from the Union of Concerned Scientists:

    Iodine-131 is one of the most radioactive isotopes released in a nuclear accident. It has a half-life of 8 days, meaning half of it will have decayed after 8 days, and half of that in another 8 days, etc. Therefore, it is of greatest concern in the days and weeks following an accident. It is also volatile so will spread easily. In the human body, iodine is taken up by the thyroid, and becomes concentrated there, where it can lead to thyroid cancer in later life. Children who are exposed to iodine-131 are more likely than adults to get cancer later in life. To guard against the absorption of iodione-131, people can proactively take potassium iodine pills so the thyroid becomes saturated with non-radioactive iodine and is not able to absorb any iodine-131.

    Cesium-137 is another radioactive isotope that has been released. It has a half-life of about 30 years, so will take more than a century to decay by a significant amount. Living organisms treat cesium-137 as if it was potassium, and it becomes part of the fluid electrolytes and is eventually excreted. Cesium-137 is passed up the food chain. It can cause many different types of cancer.

    New Scientist: How nuclear accidents damage human health.

    Reuters has a report about food implications.

  • What about the safety of the nuclear plant workers? Are there workers at the Fukushima plant being exposed to fatal levels of radiation already?

    All but 50 essential staff have now been evacuated from the plant. Those that remain are being exposed to very high levels of radiation. They are heroically staying on the job for the safety of the general public and we are deeply concerned for their safety. After the explosions in unit 1 and 3 of Fukushima !- injuries to several workers have been reported.

  • If there is widespread radioactive contamination in the area - what can people do to protect themselves?

    General instructions are to limit exposure to radioactive contamination in the event of a major release

    • Make sure you're inside a building. Close all windows as tightly as possible. The key first risk is the iodine cloud. Without rain, iodine will not be deposited on the ground and high doses could be inhaled, especially closer to the Fukushima plant.
    • Take iodine tablets only if instructed to do so or if it is clear that your area is at risk of significant contamination. Iodine pills have side effects so they should not be taken unnecessarily and should only be taken in prescribed amounts.


    For more advice please see the Center for Disease Control website.
  • Have significant levels of radiation already been recorded outside the plants? Have people been exposed to harmful levels of radiation?

    Yes. At the gate of the plant several measurements have been reported that are high enough to deliver the annual allowed dose of radiation within an hour. Several plant workers have received high doses, with at least one suffering from acute radiation sickness.

    According to the BBC:



    Local government officials say 190 people have been exposed to some radiation. An American warship, the USS Ronald Reagan detected low levels of radiation at a distance of 100 miles (161km) from the Fukushima plant.
  • Is there a safe dose of radiation? If so - at what level does radiation become unsafe?

    No there is no “safe” dose of radiation.  However, we’re all exposed to a certain amount of radiation every day.  This is called background radiation.  It comes from various sources and is unavoidable - uranium deposits, radon in brick buildings, solar rays, etc.  It’s best to avoid any additional radiation on top of this.

    The accepted standard of “allowable” radiation exposure  is 1mSv (mSv = millisievert) for the general public, and 20mSv for nuclear workers.

  • Is this Japan’s fault? Did this happen because they have old, or poorly constructed reactors built in an earthquake zone?

    Japan has some of the best engineers, and nuclear experts in the world, and their reactors are said to be designed to survive earthquakes. However, regulations about where to construct nuclear power plants have changed since the building of this reactor.

    There are many reactors of similar design in the US and Europe.  

    This is not about blame but we need to realise that nuclear technology is inherently dangerous and the potential consequences of accidents are very severe and long lasting. Nuclear power will always be vulnerable to the threats of natural disaster, design failure and human error, there are safer alternatives, nuclear power is just not worth the risk.

Basic information